Theroux finds his way in the world of autism

Many of Louis Theroux's documentaries are windows on to the worlds of subcultures such as survivalists and porn stars, but he's much more than a voyeur. I enjoy his wry, understated humour, the way he's up for anything from liposuction to bodybuilding, and his willingness to embarrass himself along the way.

You could argue Theroux has invented a new style of immersive documentary-making, where the presenter becomes part of the story. You could also argue his mild, ingenuous persona is a tactic that disarms his interviewees and eggs them on until they make fools of themselves. That may be true sometimes, but hey, you can't knock the man for making people feel comfortable and never sitting in judgment. However, I understand why there were concerns about Theroux interviewing American children from autism schools for Louis Theroux: Extreme Love - Autism, on TV ONE on Tuesday.

Writing for the Telegraph, Theroux addressed the talk. "Take a presenter known principally for his tongue-in-cheek approach to interviews and let him loose among the mentally ill.

As a concept it doesn't exactly sell itself. But the idea of working in a new way appealed to me."

The process certainly challenged Theroux in new ways. He's visibly tested by trying to interact with uncommunicative kids, and is nervous and unsure how to help during often-violent tantrums. But the father-of-two rises to the challenge, showing his humanity and compassion in a documentary that's as affecting as it is illuminating. He patiently gets to know the kids on their own terms. The closest bond he forms is with Brian, a teen who was once very violent and is now much happier. Trying to engage Brian, Theroux lines up dominoes and Brian knocks them over with glee. Later, the pair dance to a song in the car.

These lighter moments are welcome, because much here is heartbreaking. The focus is the families: their challenges and struggles, their patience and compassion, and the toll it takes. When Theroux asks the harder questions - such as whether autism makes it harder to love their children - he does so with gentleness and empathy.

New Jersey's innovative Developmental Learning Centers offer these children and their families help and hope. Showing more than telling, Theroux watches as incredibly patient specialist staff teach the kids how to socialise and how to lead independent lives. Nicky, 19, has made such progress that he's returning to a mainstream school. We see him becomes nervous, frustrated and irritable, but he's also sweet, thoughtful and funny. It's amusing when Nicky, curious about the curious stranger, reads Theroux's Wikipedia page aloud to other students. It's amusing to see the questioner being questioned, and mildly discomfited.

Theroux is visibly affected when he says his farewells. "I was leaving the world of autism with a fondness for the kids and a respect bordering on awe for the parents," he says. I felt the same - and felt more respect for Theroux than ever.